People don't realize how they have a secret love of putting themselves and others down. Believing in Teshuva takes lots of Avoda. Once this or that took place, it's all over forever! “If you or he can do such a thing, this proves who you really are!!” I know of a certain Chasidishe Rebbe who was chosen to be the heir to his father's position from among his brothers, and people wondered why.
Someone remarked about his remaining strong even during difficult times, more than his brothers. His brothers may have been more Chashuv than him, but they had a "stain" which he didn't have. What about Teshuva? According to the Torah, he is greater than his brothers!
The Rambam elaborates how mistaken people are in their underestimation of the greatness of Teshuva, and how a person can turn the worst darkness into the biggest light. Teshuva is the most incredible Chesed, which makes almost no sense; it is similar to L'maala Min HaTevah & Nisei Nissim; the utmost in Chasdei Hashem.
I have a very hard time with people who once sinned. As much as I plead with them that their Teshuva makes them even greater, and it's as if it never happened, it doesn't help them. Feelings of guilt are rampant, and are very hard to get rid of. When we see a weakness, we are quick to accuse and to look down. This is all a trick of the Yetzer Hara who loves to put you down.
Actually, the more you consider yourself: נ ַקִַיַַמִַןַה ַחֵַטְַא pure from sin, the more you feel good about yourself, and the more you can continue Shteiging. There is almost an addiction to being critical, and it takes hard work to have Ayin Tova. This is why the Torah has to say: וּב ח רְ ת ַבּ ח יִיםַַַנצביםַלַיט Chose life! It's not as obvious as it seems; people by nature love to be losers, and have self-persecution.
